Application of glycerol as a foliar spray activates the defence response and enhances disease resistance of Theobroma cacao |
| |
| Authors: | Yufan Zhang Philip Smith Siela N Maximova Mark J Guiltinan |
| |
| Institution: | 1. The Huck Institute of the Life Sciences, The Pennsylvania State University, University Park, PA, USA;2. The Department of Plant Science, The Pennsylvania State University, University Park, PA, USA;3. Metabolomics Core Facility, The Pennsylvania State University, University Park, PA, USA |
| |
| Abstract: | Previous work has implicated glycerol‐3‐phosphate (G3P) as a mobile inducer of systemic immunity in plants. We tested the hypothesis that the exogenous application of glycerol as a foliar spray might enhance the disease resistance of Theobroma cacao through the modulation of endogenous G3P levels. We found that exogenous application of glycerol to cacao leaves over a period of 4 days increased the endogenous level of G3P and decreased the level of oleic acid (18:1). Reactive oxygen species (ROS) were produced (a marker of defence activation) and the expression of many pathogenesis‐related genes was induced. Notably, the effects of glycerol application on G3P and 18:1 fatty acid content, and gene expression levels, in cacao leaves were dosage dependent. A 100 mm glycerol spray application was sufficient to stimulate the defence response without causing any observable damage, and resulted in a significantly decreased lesion formation by the cacao pathogen Phytophthora capsici; however, a 500 mm glycerol treatment led to chlorosis and cell death. The effects of glycerol treatment on the level of 18:1 and ROS were constrained to the locally treated leaves without affecting distal tissues. The mechanism of the glycerol‐mediated defence response in cacao and its potential use as part of a sustainable farming system are discussed. |
| |
| Keywords: | disease resistance glycerol application oleic acid Phytophthora capsici PR genes Theobroma cacao |
|
|
